1. Field of the Invention
The present invention relates to a method for producing 3-acetylamino-4-hydroxybenzoic acid, and the like.
2. Brief Description of the Related Art
Amino-hydroxybenzoic acid-type compounds are useful as intermediates of dyes, agricultural chemicals, pharmaceuticals, and other organic synthesized products and as a monomer for polymer polybenzoxazole with high performance and heat resistance. 3-Amino-4-hydroxybenzoic acid (3,4-AHBA) is biosynthesized in two steps by both GriI and GriH. GriI catalyzes a carbon-carbon binding reaction between a C4 compound having an amino group and a C3 or C4 compound and GriH catalyzes cyclization of a C7 compound or cyclization of a C8 compound with decarboxylation using dihydroxyacetone phosphate (DHAP) and aspartate semialdehyde (ASA) as substrates.

3,4-AHBA is unstable, and easily oxidized to form 2-aminophenoxazin-3-one-8-carboxylic acid (APOC) (see below). JP 2004-283163-A describes that when 3,4-AHBA forms as a byproduct, it is converted into APOC over time in the culture medium during production of 3-acetylamino-4-hydroxybenzoic acid (3,4-AcAHBA). However, 3,4-AcAHBA is more stable than 3,4-AHBA because 3,4-AcAHBA is stabilized by acetylation and hence avoids oxidation. 3,4-AcAHBA can easily be converted into 3,4-AHBA by treating with an acid, a base or the like. 3,4-AcAHBA can be handled more easily than 3,4-AHBA that is oxidized to form APOC and thus is unstable. Therefore, development of an excellent method for producing 3,4-AcAHBA is desirable.

JP 2004-283163-A describes that when 3,4-AHBA forms as a byproduct, it is converted into APOC over time in the culture medium during production of 3,4-AcAHBA. JP 2004-283163-A also discloses that 3,4-AcAHBA is deacetylated to form 3,4-AHBA.
International Publication WO2010/005099 discloses that 3,4-AHBA is formed by using Corynebacterium glutamicum that has been transformed with griI and griH.
J. Biol. Chem. 281 (2006), 36944-36951 discloses that 3,4-AHBA and 3,4-AcAHBA are formed by introducing griI and griH into Escherichia coli. 
J. Bacteriol. 189 (2007), 2155-2159 discloses that 3,4-AcAHBA is not formed in culture by deleting arylamine N-acetyltransferase (natA) gene in Streptomyces griseus. 
Biochim. Biophys. Acta. 1475 (2000), 10-16 discloses that N-hydroxyarylamine O-acetyltransferase (nhoA) gene derived from Escherichia coli works to catalyze acetylation for an aromatic amino group. Meanwhile, J. Antibiot., vol. 59 (2006), p. 464 discloses that E. coli BAP1 strain forms an N-acetylated product (3,5-AcAHBA) as a byproduct of 3,5-AHBA (a structural isomer of 3,4-AHBA), and also discloses that it is conceivable that NhoA is not a major factor for N-acetylation of 3,5-AHBA because 3,4-AcAHBA is also formed as a byproduct in an NhoA gene-deleted strain (MAR1 strain) of E. coli BAP1.